Hey guys, as the title says I have a 2009 Nitro 3.7L Coil-on-plug that i bought a couple weeks ago. When i bought it, it was running rough due to what I thought might be bad plugs, and was pulling a P0300 code and fuel system too rich code. I Changed the plugs as well as new coil packs, wires and injectors however, when I start it, the truck revs up and down, and it backfires every couple seconds. Could it be a vaccum leak? Any help would be appreciated.